I. Field of the Invention
The present invention relates generally to systems and methods used to dispose of and/or recycle non-hazardous waste, such as engine oil filters and oil-absorbent pads, and more particularly to such systems and methods which result in minimum adverse impact on the environment.
II. Background and Prior Art
Disposal of used engine oil filters and oil-absorbent pads presents a serious environmental problem for a number of reasons. First, these products retain residual oil which can contaminate soil in landfills or the like. Used motor oil contains toxic heavy metals such as lead, chromium and cadmium, and dangerous organic chemicals. It is estimated that every year, more than 170 million gallons of used oil is improperly disposed of. Because sewage plants are not designed to deal with used motor oil, such oil often passes through storm sewers directly into rivers, wetlands and the ocean, posing a threat to aquatic life, as well as to the drinking water sources. Further, the oil filters contain materials of different types such as metal and paper-like filter material which cannot be readily decomposed or which are difficult to decompose. For these reasons, and because most of the used motor oil comes from disposal of used oil filters from automotive vehicles and industrial machinery, there has been ongoing research for ways to easily reclaim the oil in used oil filters, and to reclaim the metals and used filter elements therefrom.
One method involves gravity draining the filters to remove a large portion of the oil, and then melting down the filters and recasting the metal as reinforcing bar. However, this type of program makes no use of the used filter elements, does not remove enough of the oil before the filters are melted down, and is an expensive process.
Another means of recycling used oil filters simply involves crushing of the filters after the oil is drained. This presents the problem of fumes from the oil left in the filters when further recycling takes place, as does the melting and recasting process previously described. Thus, there remains a need in the art for a clean economical method of recycling used oil filters.
Consequently, an improved system and method of recycling such waste materials are needed. In such an improved system, used oil filters and oil absorbent pads (the “non-hazardous waste material”) would be collected and dumped into a containment sump area. Any used oil and oily water in the waste material would be pumped out of the containment sump area to used oil storage tanks for recycling. A conveyor system in the containment sump area will take the solid waste material (metal housings and absorbent filter materials) to a sheer shredder (or “size reduction unit”) to provide a reduced sized waste material for processing. The shredded waste material will be conveyed to a dual-batching system for loading into the incinerator (sometimes referred to as the “energy recovery unit” or “ERU”). When the waste material is loaded into the incinerator, the unit must have a controlled temperature such that the metal materials are not melted. Oily water from the bottom of the used oil storage tanks would be sprayed into the incinerator during the incineration process to assist in controlling the temperature inside the incinerator hearths. Oily water would also be routed to an evaporator unit for the production of steam as will be further described herein. The steam from the boiler and evaporator would be used to provide heat to the used oil storage tanks to aid in the oil/water separation within the tanks. Any condensate from steam used in connection with the storage tanks would be re-routed back to the boiler for further production of steam.
As will be further explained below in connection with the preferred embodiments, the use of a dual-hearth system inside the incinerator would provide a cleaner and easier way to remove the fly ash and clean metal without interrupting the operation of the incinerator process. A vacuum system would also be employed to vacuum the fly ash from the hearth and the metal hopper system. Also, an overhead crane magnet would remove the clean metal from the hearth and would deliver the clean metal into a scrap metal hopper. The hopper may include a vibrating conveyor which delivers the clean metal to a scrap metal container. Preferably, the vibrating conveyor would be hooded such that the vacuum system may also remove any additional fly ash at that stage of the process.
Fully and properly implemented, it is anticipated that such a system and method would result in an essentially “zero discharge”, environmentally sound process, wherein the usable products are a non-hazardous fly ash (sellable as a stabilization material), a clean scrap metal (sellable as a #1 scrap metal), and used oil fuel (sellable to used oil bunker fuel market).